Loop takers for sewing machines



Sept. 9, 1969 L. J. KUHAiR 3,465,700"

LOOP TAKERS FOR SEWING MACHINES Filed Feb. 14. 1968 mvsmozz Ludwlg J. Kuhar 7 BY WITNESS: W dud awwsozeeew f ATT RNEY United States Patent M 3,465,700 LOOP TAKERS FOR SEWING MACHINES Ludwig .I. Kuhar, Clark, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Feb. 14, 1968, Ser. No. 705,514 Int. Cl. Db 57/14 US. Cl. 112-228 4 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The invention relates to loop takers having removable hook beaks and more particularly, to a rotary hook for a lockstitch sewing machine having a removable loop seizing beak which is adjustable circumferentially on the rotary hook.

Description of the prior art In the operation of a conventional rotary hook for a lockstitch sewing machine, a number of successive manipulations of threads are accomplished during each stitch forming cycle and each of these manipulations is required to be performed within a precise relationship of time with respect to the movements of other instrumentalities of the sewing machine such as the reciprocation of the needle, the movements of the thread take-up, etc. The needle thread loop seizing beak of the rotary hook performs one of the successive manipulations of thread in seizing thread loops from the needle. There are many occasions when the timing of the loop seizing beak is required to be adjusted relatively to the movements of the needle such as when the loop seizing beak wears, when a needle of a different character is used or the like. In conventional rotary hooks, adjustment of the loop seizing beak can be accomplished only by adjusting the relative position or timing of the entire rotary hook and this presents the disadvantage that the timing of means for accomplishing the other successive manipulations of the threads by the rotary hook must also be changed, often detrimentally.

Summary of the invention Description of the drawing FIG. 1 is an exploded perspective view of the body portion of a rotary hook incorporating the removable and circumferentially adjustable loop seizing beak of this invention.

FIG. 2 is an assembled perspective view of the rotary hook of FIG. 1, shown secured on a drive shaft.

FIG. 3 is a side elevational view of the assembled rotary hook of FIG. 2 including a bobbin case journaled in the rotary hook, and

3,465,700 Patented Sept. 9, 1969 FIG. 4 is a rear elevational view of the rotary hook of FIG. 3.

Description of the preferred embodiment With reference to the drawing, a rotary hook is illustrated of the type used in high speed lockstitch sewing machines. The loop taker includes a body portion 20 including a hub 21 formed with a bore 22 accommodating a drive shaft 23 for the rotary hook. Extending from the hub 21 is an annular cup shaped flange 24 of which a segmental portion is cut away as indicated at 25 in FIG. 1. The cup shaped flange 24 is formed interiorly with an annular bearing raceway 26 for a bearing rib 27 of a bobbin case 28 which is adapted to be constrained from rotation. In one portion of the flange 24 the complete bearing raceway 26 is cut, while in another portion of the flange 24 only half of the raceway 26 is formed, the other half being formed on a gib 29 which is secured to the flange 24 by screws 30 and may be removed to permit exchange of the bobbin case. The gib 29 is usually provided with a tail 31 projecting freely into the cutaway portion 25 of the loop taker body.

Secured exteriorly on the loop taker body flange 24 by Screws 32 is a thread camming plate 33 having an outer edge 34 which serves not only to urge seized needle thread loops outwardly over the exposed face of the bobbin case during stitch formation, but also provides a bobbin thread pull off. As illustrated in FIG. 1, one ex tremity 35 of the thread camming plate 33 extends from the cutaway portion 25 of the loop taker flange 24 to the outer edge 34 at an angle of approximately 45 to the axis of the rotary hook. The inclination of the extremity 35 extends outwardly and in a direction opposite that which the hook beak 42 faces.

As shown in the drawing, the hub 21 of the loop taker body is secured fast on the drive shaft 23 by a pair of set screws 36 threaded into the hub. The drive shaft 23, which is adapted to be turned in a clockwise direction as viewed in FIGS. 2 and 4, may from part of the actuating mechanism of any conventional high speed lockstitch sewing machine in which the loop taker partakes of two revolutions for each needle reciprocation. Since this actuating mechanism may be conventional in every respect, it is not included in the drawing of this invention, however, it will be appreciated that a precise angular position of the hook body on the drive shaft is required so that a number of relationships may be maintained in predetermined timing, i.e., the position of the cut away portion 25 of the hook flange, the position of the thread camming plate 33, and the position of the gib tail 31, all of which are required to move in accurately timed relationship with respect to the actuating mechanism and the other stitch influencing instrumentalities operated thereby.

The construction of the needle loop seizing beak of this invention will now be described and the manner in which it may be removed and adjusted circumferentially of the loop taker body without disturbing the timing of the remander of the loop taker. The loop taker has a circumferential slideway in the form of an annular groove 40 around the hub 21, within which groove a tapped hole 41 is formed in the hub. A beak carrier bracket 42 which is formed with a guide rib 43 on the underside of the bracket is mounted on the loop taker hub with the guide rib 43 seated in the annular groove 40. The bracket is removably connected to the loop taker by a screw 44 which extends through a clearance slot 45 in the bracket 42 into the tapped hole 41 in the loop taker hub.

The bracket 42 is formed with a needle loop seizing beak 46 and adjacent to the beak is formed with a raised boss 47. Two tapped holes 48 in the raised boss accommodate fastening screws 49 by which a thread camming plate extension 50 is secured to the bracket 42. As illustrated in FIG. 2, the thread camming plate extension 50 is formed with an inclined extremity 51 complemental to the inclined extremity 35 of the thread camming plate 33 on the loop taker body. The thread camming plate extension is also formed with an outer edge 52 which provides a continuation of the outer edge 34 of the camming plate 33 and with a tapered free extremity 53 which extends alongside the needle loop seizing beak.

In operation, when it is desired to make a fine adjustment of the needle loop seizing beak 46 relative to the sewing machine actuating mechanism, the screw 44 which connects the beak to the loop taker body can simply be loosened and the beak shifted in the annular groove 40 in the loop taker hub because of the clearance slot 45 in the beak carrying bracket 42. Moreover, should the beak become worn to the point where further adjustment is impossible, it can easily be replaced by removing the screw 44.

Since the extremity 35 of the thread camming plate 33 and the complemental extremity 51 of the thread camming plate extension 50 are inclined, as illustrated in the drawings, at approximately 45 in a direction opposite that of the direction of rotation of the loop taker, the space between the extremities 35 and 51 will not impede passage of thread thereover.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts can be resorted to without departing from the spirit and the scope of the invention.

Having thus set forth th nature of this invention, what I claim herein is:

1. A circularly moving loop taker for a sewing machine comprising a body portion including a hub formed with a shaft accommodating bore and a cup shaped flange formed with a bobbin case bearing race, shaft fastening means on said hub, said cup shaped flange being formed with a segmental cut-away portion, a bracket, a hook beak carried by said bracket and disposed within the cutaway portion of said cup shaped flange, and means for securing said bracket in one of a selected range of positions circumferentially of said body portion and at said cut-away portion of said flange.

2. A circularly moving loop taker for a sewing machine as set forth in claim 1 in which said means for securing said bracket on said body portion comprises mating annular guide means formed on said body portion hub and on said bracket, an elongate opening through said bracket and its said annular guide means, said opening being elongate circumferentially, and a headed fastening screw passing through said elongate opening and threaded into said hub.

3. A circularly moving loop taker for sewing machines as set forth in claim 2 in which said mating annular guide means includes an annular groove formed in the hub of said rotary hook body portion, and a guide rib projecting from said bracket member.

4. A circularly moving loop taker for a sewing machine as set forth in claim 1 in which a thread camming plate is secured exteriorly on the cup shaped flange of said body portion, said thread camming plate being formed with an extremity adjacent to said segmental cut away portion of said cup shaped flange which extremity extends at an inclination to the axis of rotation of said rotary book outwardly of said cup shaped flange and in a direction opposite that which said hook beak faces, and in which a thread camming plate extension is carried on said bracket and formed with an extremity which is complemental to and spaced from said inclined extremity of said thread camming plate on said cup shaped flange.

References Cited UNITED STATES PATENTS 1,431,380 10/1922 Dickson 1l2--228 2,716,956 9/1955 Parry 1l2--230 3,139,050 6/ 1964 Grabowski l12228 3,215,105 11/1965 Kuhar 112-228 3,223,060 12/1965 Corey 112-228 ALFRED R. GUEST, Primary Examiner 

